Manufacturing method of semiconductor device and electronic device

ABSTRACT

Silicide films with high quality are formed with treatment of laser light irradiation, so that miniaturization and higher performance is achieved in a field-effect transistor that is formed over an insulating substrate and has little variation in electric characteristics. An island-shaped semiconductor film including a pair of impurity regions and a channel formation region is formed over an insulating substrate, a first metal film is formed on the pair of impurity regions, and a second metal film that functions as a reflective film is formed over a gate electrode located over the channel formation region with a gate insulating film interposed therebetween. The first metal film is irradiated with laser light and a region where the second metal film is formed reflects the laser light, so that the island-shaped semiconductor film and the first metal film selectively react with each other in the pair of impurity regions.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for manufacturing asemiconductor device, and to an electronic device having thesemiconductor device.

2. Description of the Related Art

With high integration of large scale integration (LSI), miniaturizationof each element (e.g., transistors) constituting LSI is required. As thesize of elements is reduced to miniaturize transistors, a problem called“short channel effect” stands out. A short channel effect results in adrop in threshold voltage or an increase in leakage current, so thatunfortunately, reliability of the elements declines.

As measures to suppress the short channel effect, thinning of asemiconductor film which functions as an active layer and a gateinsulating film has been under consideration. If a semiconductor filmand a gate insulating film are thinned, low contact resistance isrequired between a metal wiring and the semiconductor film or in animpurity region of the semiconductor film. Therefore, a technique tolower contact resistance or resistance of an impurity region (a sourceregion and a drain region) by forming a silicide film in a semiconductorfilm has been employed in the semiconductor field. With low resistancein a semiconductor film, an on-current is increased in a semiconductordevice, and thus a semiconductor device with excellent characteristicscan be manufactured.

In order to silicide a semiconductor film, a method is generally takenin which a metal film is formed on a semiconductor film and heattreatment is performed to make the films react with each other, so thata silicide film is formed at an interface between the semiconductor filmand the metal film. However, a thermal process has a problem in that adegree of freedom of selecting a substrate is lowered depending on theheat resistance of the substrate. Further, it is difficult to form asilicide film with high quality by heat treatment at a low temperature(e.g., 450 to 750° C.). In view of the above problem, a technique isattempted in which laser light irradiation is performed with asemiconductor film and a metal film in contact with each other, to makethe films react with each other at a high temperature in a short time,so that a silicide film with high quality is formed without thermaldamage to a substrate (for example, see Reference 1: Japanese PublishedPatent Application No. 2000-277750).

However, when a silicide film was provided, using the above laser lightirradiation, for a miniaturized structure, i.e., a structure in which asemiconductor film and a gate insulating film are thinned, a problem wascaused in which the semiconductor film in a region overlapping with agate electrode tends to be lost. FIGS. 6A and 6B show transmissionelectron microscopy (TEM) photographs of a thin film transistor(hereinafter, referred to as a TFT) in which a thin semiconductor filmformed over a glass substrate is irradiated with laser light. FIG. 6B isan enlarged photograph of a part of FIG. 6A. In FIGS. 6A and 6B, in theobserved TFT, a gate insulating film and a semiconductor film in aregion overlapping with a gate electrode are lost, as designated by adotted circle.

Now a process of manufacturing the TFT in FIGS. 6A and 6B is presentedbelow. First, a silicon oxynitride film which functions as a baseinsulating film 602 was formed with a thickness of 100 nm over a glasssubstrate 601, and an island-like semiconductor film 603 was formed witha thickness of 25 nm over the base insulating film. Then, in thefollowing order, a gate insulating film with a thickness of 5 nm wasformed over the island-like semiconductor film 603, and a gate electrode605 having a stacked-layer structure of tantalum nitride with athickness of 30 nm and tungsten with a thickness of 130 nm was formedover the island-like semiconductor film with the gate insulating filminterposed therebetween. After that, a silicon oxynitride film wasformed so as to cover the gate electrode and the silicon oxynitride filmwas etched, so that sidewall insulating layers 606 were formed at sidesurfaces of the gate electrode.

Next, an impurity element (phosphorus in this case) was introduced in aself-aligned manner using the gate electrode 605 and the sidewallinsulating layers 606 as masks, so that a pair of impurity regions wereformed in the island-like semiconductor film 603. Then, the entiresubstrate was irradiated with an excimer laser. FIGS. 6A and 6B are TEMphotographs of a cross section of the TFT observed after the irradiationwith the excimer laser.

As described above, in the TFT shown in FIGS. 6A and 6B, the gateinsulating film and the semiconductor film in a region overlapping withthe gate electrode were lost. The present inventors ascribe thephenomenon in FIGS. 6A and 6B to the following cause: when the metal,which is the gate electrode, absorbs the laser light and generates heat,a temperature of the semiconductor film is thought to cross a boilingpoint because the semiconductor film, which is thinned to have smallerthermal capacity, is heated indirectly. Not only the semiconductor filmof a source region and a drain region, but the gate electrode was alsoheated in the laser light irradiation. A transistor with a miniaturizedstructure has small thermal capacity due to the thinned semiconductorfilm. Further, the semiconductor film under a gate electrode is alsoheated by heat conducted from the gate electrode because a gateinsulating film is also thinned.

SUMMARY OF THE INVENTION

In view of the above problem, it is an object of the present inventionto realize miniaturization and higher performance of field effecttransistors, which are formed over an insulating substrate and withwhich there is little variation in electric characteristics, in which asilicide film with high quality is formed by treatment using laser lightirradiation.

The present invention prevents a semiconductor film from being lost bylaser light irradiation, by the following methods.

An aspect of a method for manufacturing a semiconductor device accordingto the present invention is that a film for reflecting laser light isformed in a portion where a crystalline semiconductor film and a metalfilm are not in contact with each other, in particular, over the gateelectrode so that a portion where a silicide film is formed in thecrystalline semiconductor film, i.e., a portion where the crystallinesemiconductor film and the metal film are in contact with each other, isselectively irradiated with the laser light.

Further, another aspect of a method for manufacturing a semiconductordevice according to the present invention is that a heat conductive filmfor conducting thermal energy of laser light in a lateral direction (ina plane direction of the film) is formed in a portion where acrystalline semiconductor film and a metal film are not in contact witheach other, in particular, over the gate electrode so that a portionwhere a silicide film is formed in the crystalline semiconductor film isselectively irradiated with the laser light.

In the method for manufacturing a semiconductor device according to thepresent invention, a short-channel effect is suppressed because thesemiconductor film of a channel formation region is thinned, while apair of impurity regions (a source region and a drain region), i.e., thesemiconductor film in a region where a silicide film is formed at aninterface between the semiconductor film and a metal film, is thickerthan the semiconductor film of the channel formation region so that thepair of impurity regions (the source region and the drain region) havelarge thermal capacity. When an island-like semiconductor film has abump, the thickness of the pair of impurity regions or that of thechannel formation region is defined by the largest thickness amongthicknesses of the semiconductor film constituting each region.

In the above manner, by a silicide method using laser light irradiation,a silicide film can be formed at an interface between a semiconductorfilm of a pair of impurity regions (a source region and a drain region)and a metal film without losing the semiconductor film in a regionoverlapping with a gate electrode.

In this specification, “silicide” means a compound in general of asemiconductor and a metal as well as a compound of silicon and a metal.

According to the present invention, a silicide film can be formed bylaser light irradiation without losing a semiconductor film under a gateelectrode.

Further, with the use of laser light for making silicide, a process canproceed with higher controllability by appropriately setting a pulsewidth or parameter of laser power, whereby a desired silicide film canbe formed. Furthermore, by using laser light, a silicide film withhigher quality can be formed, in comparison to the use of a thermalprocess, without having to worrying about thermal damage to a substrate.

Therefore, with application of the present invention, miniaturizationand higher performance of a field-effect transistor can be realized.

BRIEF DESCRIPTION OF DRAWINGS

In the accompanying drawings:

FIG. 1 is a diagram showing an example of a flow of a method formanufacturing a semiconductor device according to the present invention;

FIGS. 2A to 2D are diagrams showing an example of a method formanufacturing a semiconductor device according to the present invention;

FIGS. 3A to 3D are diagrams showing an example of a method formanufacturing a semiconductor device according to the present invention;

FIG. 4 is a diagram showing an example of a flow of a method formanufacturing a semiconductor device according to the present invention;

FIGS. 5A to 5D are diagrams showing an example of a method formanufacturing a semiconductor device according to the present invention;

FIGS. 6A and 6B are TEM photographs of a cross section of a TFTmanufactured by a conventional method;

FIG. 7 is a block diagram showing an example of a semiconductor deviceof the present invention;

FIG. 8 is a cross-sectional view showing an example of a semiconductordevice of the present invention;

FIG. 9 is a perspective view showing an example of a semiconductordevice of the present invention;

FIG. 10A is a top view, and FIGS. 10B and 10C are cross-sectional viewsshowing an example of a semiconductor device of the present invention;

FIGS. 11A to 11D are diagrams illustrating antennas which can be appliedto a semiconductor device of the present invention;

FIG. 12A is a block diagram of an example of a semiconductor device ofthe present invention, and FIGS. 12B and 12C are diagrams showingexamples of usage modes of a semiconductor device of the presentinvention; and

FIGS. 13A to 13H are diagrams showing application examples of asemiconductor device of the present invention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment Modes

Hereinafter, embodiment modes of the present invention are describedwith reference to the drawings. Note that the present invention can beperformed in many different modes and it is easily understood by thoseskilled in the art that the modes and details disclosed herein can bemodified in various ways without departing from the spirit and scope ofthe present invention. Therefore, the present invention should not beinterpreted as being limited to the description of the embodiment modesto be given below.

Embodiment Mode 1

The present invention relates to a process of forming a semiconductorelement having a silicide film, over a substrate having an insulatingsurface. FIG. 1 shows an example of a flow chart illustrating a methodfor manufacturing a semiconductor device according to the presentinvention.

First, an island-like crystalline semiconductor film is formed over aninsulating substrate (St 1). Next, a gate insulating film is formed overthe island-like crystalline semiconductor film (St 2), and a gateelectrode is formed over the gate insulating film (St 3). An impurityelement is introduced using the gate electrode as a mask to form asource region and a drain region, and then an interlayer insulating filmis formed over the gate electrode (St 4). Then, contact holes whichexpose at least a portion of each of the source region and the drainregion in the island-like crystalline semiconductor film are formed inthe interlayer insulating film (St 5). Subsequently, a first metal film,and a second metal film that functions as a reflective film are formedso as to cover the exposed source region and drain region and theinterlayer insulating film (St 6). Next, the second metal film locatedover the source region and drain region is etched (St 7). Then, thefirst metal film is irradiated with laser light to form silicide filmsselectively over the source region and drain region (St 8). In a regionwhere the second metal film that functions as a reflective film isformed, laser light is reflected; therefore, thermal damage by laserlight irradiation to the crystalline semiconductor film located underthe second metal film can be alleviated. Note that the steps shown inFIG. 1 are not necessarily performed independently, and a plurality ofsteps may be performed consecutively.

Hereinafter, in this embodiment mode, a concrete example of a method offorming a silicide film by laser light irradiation in a top gate TFT isdescribed with reference to FIGS. 2A to 3D.

First, an insulating film 102 which functions as a base film is formedover one surface of an insulating substrate 101 (see FIG. 2A). Theinsulating film 102 which functions as a base film is formed using asilicon oxide film, a silicon nitride film, a silicon nitride oxidefilm, a silicon oxynitride film, or the like as appropriate as a singlelayer or stacked layers with a thickness of 50 to 150 nm. In thisembodiment mode, as the substrate having an insulating surface, a glasssubstrate with a thickness of 0.7 mm is used, for example. As theinsulating film 102 which functions as a base film, a silicon nitrideoxide film with a thickness of 150 nm is formed. The insulating film 102can be formed by a CVD method typified by a plasma CVD method or alow-pressure CVD method, a sputtering method, or the like.

In this specification, “silicon oxynitride” means a substance in whichthe oxygen content is higher than the nitrogen content, and can also bereferred to as “silicon oxide containing nitrogen.” Further, in thisspecification, “silicon nitride oxide” means a substance in which thenitrogen content in higher than the oxygen content, and can also bereferred to as “silicon nitride containing oxygen.”

Next, an amorphous semiconductor film is formed as a semiconductor film103 over the insulating film 102. In a similar manner to the insulatingfilm 102, the semiconductor film 103 may be formed by a CVD method, asputtering method, or the like. In this embodiment mode, an amorphoussilicon film with a thickness of 66 nm is formed by a plasma CVD method.

The insulating film 102, which functions as a blocking film forpreventing impurities from diffusing, may be provided as necessary. In acase where the insulating substrate 101 is a glass substrate containingimpurities, in particular, movable ions which easily move, theinsulating film 102 prevents the impurities from the glass fromdiffusing into the semiconductor film; however, in a case where a quartzsubstrate is used as the insulating substrate 101, it is not necessaryto provide the insulating film 102 which functions as a blocking film.

Further, if an interface between the insulating film 102 and thesemiconductor film 103 is not exposed to air in forming thesemiconductor film 103 over the insulating film 102, contamination ofthe interface can be prevented, whereby variation in characteristics ofTFTs to be manufactured can be reduced.

Next, the amorphous silicon film, which is the semiconductor film 103,is crystallized. In this embodiment mode, the semiconductor film 103 iscrystallized by being scanned with continuous wave laser light arrangedto have a linear form at an irradiation surface with an optical system.Through the above step, a crystalline semiconductor film can be formed.In order to enhance resistance of a semiconductor film against laserlight, thermal treatment for reducing hydrogen in the semiconductor filmmay be performed before laser light irradiation. Further, thecrystallization treatment is not limited to a laser crystallizationmethod; and a thermal crystallization method using RTA, an annealingfurnace, or the like, a thermal crystallization method using a catalystsuch as nickel, or the like can be used.

Next, the semiconductor film 103 is selectively etched through aphotolithography process, so that an island-like crystallinesemiconductor film 104 is formed. Further after that, as shown in FIG.2B, only a portion of the semiconductor film (in FIG. 2B, a region 104B)is etched to be thin through a photolithography process, so that aregion 104A and a region 104C, which function as a source region and adrain region, and the region 104B, which functions as a channelformation region, are formed. It is preferable that the region 104B,which functions as the channel formation region, has a thickness ofabout 10 to 30 nm. In the island-like crystalline semiconductor film104, a short-channel effect can be suppressed by making the thickness ofthe channel formation region thin. Further, thermal capacity can belarge by making the thicknesses of the source region and the drainregion larger than a thickness of the channel formation region.

Further, if necessary, in order to control a threshold value of the TFT,the semiconductor film 103 may be doped with a small amount of impurityelement imparting one type of conductivity (e.g., boron or phosphorus)before etching the semiconductor film 103 selectively.

For the island-like crystalline semiconductor film 104, an SOI substrateobtained by providing a single-crystalline semiconductor layer for aninsulating surface may be used instead of performing a thin filmprocess, in which a variety of crystallization methods are used. In thiscase, the island-like crystalline semiconductor film 104 can be formedusing a single-crystalline semiconductor layer provided for aninsulating surface.

Next, a surface of the island-like crystalline semiconductor film 104 iswashed with an etchant containing hydrofluoric acid, and then a gateinsulating film 105 is formed over the island-like crystallinesemiconductor film 104. The gate insulating film 105 is formed using aninsulating film containing silicon as a main component. It is preferableto perform the surface washing step and the gate insulating filmformation step sequentially without exposure to air.

After washing a surface of the gate insulating film 105, a conductivelayer is formed over the gate insulating film 105. The conductive layeris formed by a CVD method or a sputtering method using a conductivematerial. As the conductive material, a metal element such as tantalum(Ta), tungsten (W), titanium (Ti), molybdenum (Mo), chromium (Cr),aluminum (Al), copper (Cu), or niobium (Nb), or an alloy or compoundmaterial containing the above metal element can be used. Further, asemiconductor material, such as polycrystalline silicon to which animpurity element imparting one type of conductivity such as phosphorushas been added, can also be used. The conductive layer formed over thegate insulating film 105 may have either a single-layer structure or astacked-layer structure. The conductive layer has a thickness (the totalthickness thereof, if the conductive layer has a stacked-layerstructure) of 50 to 1000 nm, preferably 100 to 800 nm, more preferably200 to 500 nm.

Next, a photoresist film is applied over the conductive film andundergoes light exposure and development, so that a resist pattern isformed. The conductive film is etched using the resist pattern as amask, so that a gate electrode 106 is formed over the gate insulatingfilm 105 (see FIG. 2C).

Next, using the gate electrode 106 as a mask, n-type impurity ions (ionsof P, As, or the like; P ions in this embodiment mode) are introducedinto the island-like crystalline semiconductor film 104 through the gateinsulating film 105, so that a source region and a drain region areformed.

Next, an interlayer insulating film 107 is formed over an entire surfaceincluding the gate insulating film 105 and the gate electrode 106, andthen hydrogenation is performed (see FIG. 2D). Subsequently, a resistpattern is formed over the interlayer insulating film 107. Using theresist pattern as a mask, the interlayer insulating film 107 and thegate insulating film 105 are etched, so that contact holes 108 whichexpose at least a portion of each of the source region and the drainregion are formed (see FIG. 3A).

After that, the exposed surface of the island-like crystallinesemiconductor film 104 is washed with hydrofluoric acid. Next, a firstmetal film 109 is formed over an entire surface by a sputtering methodso as to cover the exposed portions of the island-like crystallinesemiconductor film 104. Subsequently, a second metal film 110 thatfunctions as a reflective film is formed over the first metal film 109.The first metal film 109 and the second metal film 110 each have athickness of 5 to 30 nm. The first metal film 109 is formed using amaterial which can form a silicide film at an interface between thefirst metal film 109 and the crystalline semiconductor film 104 by laserlight irradiation in a later step. As a material of the first metal film109, Ni, Co, Ti, or Pt can be used, for example. For the second metalfilm 110 that functions as a reflective film, a material which havehigher reflectance to a wavelength of the laser light with whichirradiation is performed in a later step than that of the first metalfilm can be used. In a case where an excimer laser is used as a laser,for example, aluminum, an aluminum alloy, silver, a silver alloy, or thelike can be used as a material of the second metal film 110. Further,instead of the second metal film 110, stacked layers of a silicon oxidefilm, a silicon nitride film, and the like may be formed to function asreflective films by a thin film interference effect.

Next, the second metal film 110 located over the source region and thedrain region in the island-like crystalline semiconductor film 104 isetched by a known photolithography technology (see FIG. 3C).

Subsequently, the first metal film 109 is irradiated with laser lightfrom above the top surface of the second metal film 110 (see FIG. 3D).In the laser light irradiation, laser light emitted from a laseroscillator is arranged to be a linear beam by an optical system, andthen is scanned in a minor axis direction of the linear form. As thelaser oscillator, a variety of excimer laser oscillators such as XeCl,KrCl, KrF, ArF, or XeF can be preferably used.

The linear beam means laser light having a linear beam spot on anirradiation surface. The term “linear” used herein does not mean a linein a strict sense, but means a rectangular shape having a high aspectratio (e.g., an aspect ratio of 10 or more (preferably, 100 or more)).The laser light is shaped into the linear beam in order to securesufficient energy density with respect to an irradiation object. Whensufficient energy density can be secured, the laser light may be shapedinto a rectangular or ellipsoid beam.

When the first metal film 109 is irradiated with laser light, the secondmetal film 110 reflects the laser light, functioning as a reflectivefilm. Therefore, thermal damage to the gate electrode 106 and thecrystalline semiconductor film (including the channel formation region)in a region overlapping with the gate electrode 106, which are locatedunder the second metal film 110, can be prevented. In the source regionand the drain region, over which the second metal film 110 is etchedaway, a silicide reaction occurs at an interface between the crystallinesemiconductor film 104 and the first metal film 109, so that silicidefilms 111 are formed in the source region and the drain region of thecrystalline semiconductor film 104. As described above, the silicidefilms 111 can be formed in the source region and the drain regionwithout losing the semiconductor film of the channel formation region.

Through the above process of forming a silicide film, resistance can belowered sufficiently in the source region and drain region of thecrystalline semiconductor film 104. After that, therefore, it is notnecessary to activate the introduced n-type impurity element. However,it is needless to say that heat treatment may be performed in order toactivate the impurity element added to the crystalline semiconductorfilm 104. The heat treatment can be performed by laser beam irradiation,RTA, or using an annealing furnace. Concretely, the heat treatment maybe performed at temperatures of 400 to 700° C., preferably 500 to 650°C. Further, the heat treatment is preferably performed in a nitrogenatmosphere. For example, activation can be performed by heating at 550°C. for four hours. If the impurity element is activated by laser beamirradiation, an excimer laser can be used, for example.

After forming the silicide films 111, the first metal film 109 unreactedand the second metal film 110 unreacted are etched away. Next, aconductive film (e.g., an Al alloy wiring) is formed over the interlayerinsulating film and in the contact holes, and is patterned, so that asource electrode and a drain electrode are formed. Through the abovesteps, a TFT (n-channel TFT) is formed.

The present invention is not limited to the TFT structure shown in thisembodiment mode, and can also be applied to a TFT having a differentstructure. For example, a lightly doped drain (LDD) structure having anLDD region between a channel forming region and a drain region (or asource region) may be employed. This structure has a region to which animpurity element is added at a low concentration (hereinafter, referredto as an LDD region) between a channel forming region and a sourceregion, or between the channel formation region and a drain region.Alternatively, a gate-drain overlapped LDD (GOLD) structure, in which anLDD region overlaps with a gate electrode with a gate insulating filminterposed therebetween, may be employed.

Although this embodiment mode describes a case of an n-channel TFT, itis needless to say that a p-channel TFT can be formed using a p-typeimpurity element instead of the n-type impurity element. In addition,although this embodiment illustrates a top-gate TFT as an example, thepresent invention can be applied to an inversely-staggered TFT, forexample.

In a method for manufacturing a semiconductor device according to thepresent invention, with the use of laser light for making silicide, aprocess can proceed with higher controllability by appropriately settinga pulse width or parameter of laser power, whereby a desired silicidefilm can be formed. With the use of laser light, furthermore, incomparison with a thermal process, a silicide film with higher qualitycan be formed without thermal damage to a substrate.

In a case where laser light irradiation is performed with a thinnedsemiconductor film in contact with a metal film, the semiconductor filmcan be lost. However, in the method for manufacturing a semiconductordevice according to the present invention, a short-channel effect issuppressed because a semiconductor film in a region which functions as achannel formation region of a TFT is thinned; in contrast, a sourceregion and a drain region, i.e., the semiconductor film in regions wheresilicide films are formed, are thicker than the semiconductor film ofthe channel formation region so that the source region and the drainregion have large thermal capacity; thus, the semiconductor film can beprevented from being lost in laser light irradiation.

With the use of the method for manufacturing a semiconductor deviceaccording to the present invention, thermal damage to a gate electrodeand to the semiconductor film in a region overlapping with the gateelectrode can be reduced and silicide films can be formed in the sourceregion and the drain region. In particular, the present invention iseffective in a miniaturized TFT, i.e., a TFT in which a gate insulatingfilm or a semiconductor film of a channel formation region is thinned.

Embodiment Mode 2

This embodiment mode illustrates an example of a method formanufacturing a semiconductor device according to the present invention,which is different from Embodiment Mode 1. FIG. 4 is an example of aflow chart illustrating a method for manufacturing a semiconductordevice according to the present invention. Description is made withsteps which overlaps with Embodiment Mode 1 simplified or omittedpartly.

First, in a similar manner to the manufacturing steps of Embodiment Mode1 shown in FIG. 1, contact holes which expose at least a portion of asource region and a portion of a drain region in an island-likecrystalline semiconductor film are formed in an interlayer insulatingfilm formed over a gate electrode (St 10). Subsequently, a first metalfilm, which functions as a heat conductive film, is formed so as tocover the exposed source and drain regions and the interlayer insulatingfilm (St 11). Next, the first metal film located over the source regionand drain region is etched (St 12). Then, a second metal film thatcovers the first metal film, the source region, and the drain region isformed (St 13). Next, the second metal film is irradiated with laserlight, so that silicide films are formed selectively in the sourceregion and the drain region (St 14). The first metal film is formedusing a material with higher heat conductivity than the second metalfilm. With the use of a material with higher heat conductivity than thesecond metal film for the first metal film, in a region where the firstmetal film is formed, energy of the laser light with which the firstmetal film is irradiated through the second metal film is conducted in aplane direction of the first metal film; thus, thermal damage due to thelaser light irradiation to the crystalline semiconductor film locatedunder the first metal film can be alleviated. Note that the steps shownin FIG. 4 are not necessarily performed independently, and a pluralityof steps may be performed consecutively. In this specification, a heatconductive film means a metal film which is formed using a material withhigher heat conductivity than a metal film for forming a silicide film.

According to this embodiment mode, hereinafter, an example in which asilicide film is formed by performing laser light irradiation in a topgate TFT is illustrated concretely with reference to FIG. 5A to 5D.Steps up to forming contact holes in an interlayer insulating filmcovering a gate electrode can be performed by a similar manufacturingmethod to the steps illustrated using FIGS. 2A to 2D in Embodiment Mode1, so that description thereof is omitted in this embodiment mode.

An insulating film 102, an island-like crystalline semiconductor film104, a gate insulating film 105, a gate electrode 106, and an interlayerinsulating film 107 are formed over an insulating substrate 101, andthen contact holes 108 are formed in the interlayer insulating film 107.The contact holes 108 are formed in the following manner: a resistpattern is formed over the interlayer insulating film 107, and theinterlayer insulating film 107 and the gate insulating film 105 areetched using the resist pattern as a mask. The contact holes 108 exposeat least a portion of a source region and a portion of a drain region.An exposed surface of the island-like crystalline semiconductor film 104is washed with hydrofluoric acid, and then a first metal film 409 isformed with a thickness of 5 to 30 nm over an entire surface so as tocover the exposed portions of the island-like crystalline semiconductorfilm 104 (see FIG. 5A). The first metal film 409 can be formed by asputtering method, for example.

Subsequently, the first metal film 409 located over the source regionand the drain region in the island-like crystalline semiconductor film104 is etched by a photolithography technology (see FIG. 5B). Afterthat, a second metal film 410 is formed with a thickness of 5 to 30 nmover an entire surface of the insulating substrate 101 so as to coverthe exposed source region and the exposed drain region (see FIG. 5C).

The first metal film 409 is formed using such a material that canfunction as a heat conductive film for laser light with whichirradiation is performed in a later step. For the first metal film 409,a material with higher heat conductivity than the second metal film 410can be used: for example, copper, iron, or aluminum; an alloy compoundcontaining any of the above metals; or stainless steel can be preferablyused. The second metal film 410 is formed using such a material that canform a silicide film at an interface between the second metal film 410and the crystalline semiconductor film 104 by laser light irradiation ina later step. As a material of the second metal film 410, Ni, Co, Ti, orPt can be used, for example.

Subsequently, laser light irradiation is performed from above the topsurface of the second metal film 410 (see FIG. 5D). In the laser lightirradiation, laser light emitted from a laser oscillator is arranged tobe a linear beam by an optical system, and then is scanned in adirection of a minor axis of the linear form. As the laser oscillator, avariety of excimer laser oscillators such as XeCl, KrCl, KrF, ArF, orXeF can be preferably used.

The first metal film 409 is formed using a material with higher heatconductivity than the second metal film 410; therefore, energy of thelaser light with which the first metal film 409 is irradiated throughthe second metal film 410 is apt to be conducted in a plane direction ofthe first metal film 409, so that thermal damage to the gate electrode106 located under the first metal film 409 and to the crystallinesemiconductor film in a region overlapping with the gate electrode 106(in particular, the channel formation region) can be prevented. In thesource region and drain region located in regions which do not overlapwith the first metal film 409, a silicide reaction occurs at aninterface between the crystalline semiconductor film and the secondmetal film 410, whereby silicide films 411 are formed in the sourceregion and the drain region of the crystalline semiconductor film. Asdescribed above, the silicide films 411 can be formed at an interfacebetween the source region and the second metal film 410 and at aninterface between the drain region and the second metal film 410 withoutlosing the semiconductor film of the channel formation region.

Through the above process of forming silicide films, resistance can belowered sufficiently in the source region and drain region of thecrystalline semiconductor film 104. After that, therefore, it is notnecessary to activate an introduced n-type impurity element. However, itis needless to say that heat treatment, strong light irradiation, orlaser light irradiation may be performed in order to activate the n-typeimpurity element.

After forming the silicide films 411, the first metal film 409 unreactedand the second metal film 410 unreacted are etched away. Next, aconductive film (e.g., an Al alloy wiring) is formed over the interlayerinsulating film and in the contact holes and is patterned, so that asource electrode and a drain electrode are formed. Through the abovesteps, a TFT (n-channel TFT) is formed.

An embodiment mode of the present invention is not limited to the above.For example, the following steps may be taken: after forming the contactholes in the interlayer insulating film, the first metal film forforming the silicide films is formed entirely so as to cover the sourceregion and the drain region; subsequently, the second metal film, whichfunctions as a heat conductive film, is formed over the first metalfilm; and then, the second metal film over the source region and thedrain region is etched away. In this case, when laser light irradiationis performed from above the top surface of the second metal film, in aregion where the second metal film is formed, energy of the laser lightis conducted in a plane direction of the second metal film. In thesource region and the drain region, over which the second metal film isnot formed, silicide films are formed at an interface between the sourceregion and the first metal film and at an interface between the drainregion and the first metal film. In other words, the manufacturingmethod described herein is similar to Embodiment Mode 1, and in themanufacturing method described herein, the second metal film functionsas a heat conductive film.

The present invention is not limited to the TFT structure shown in thisembodiment mode, and can also be applied to a TFT having a differentstructure.

In a method for manufacturing a semiconductor device according to thepresent invention, with the use of laser light for making silicide, aprocess can proceed with higher controllability by appropriately settinga pulse width or parameter of laser power, whereby a desired silicidefilm can be formed. With the use of laser light, furthermore, a silicidefilm with higher quality can be formed without thermal damage to asubstrate, in comparison with a thermal process.

In a case where laser light irradiation is performed with a thinnedsemiconductor film in contact with a metal film, the semiconductor filmcan be lost. However, in the method for manufacturing a semiconductordevice according to the present invention, a short-channel effect issuppressed because a semiconductor film in a region which functions as achannel formation region of a TFT is thinned; in contrast, a sourceregion and a drain region, i.e., the semiconductor film in regions wheresilicide films are formed, are thicker than the semiconductor film ofthe channel formation region so that the source region and the drainregion have large thermal capacity; thus, the semiconductor film can beprevented from being lost in laser light irradiation.

With the use of the method for manufacturing a semiconductor deviceaccording to the present invention, thermal damage to a gate electrodeand to the semiconductor film in a region overlapping with the gateelectrode can be reduced and silicide films can be formed in the sourceregion and the drain region. In particular, the present invention iseffective in a miniaturized TFT, i.e., a TFT in which a gate insulatingfilm or a semiconductor film of a channel formation region is thinned.

Embodiment Mode 3

A semiconductor device manufactured according to the present inventioncan be applied to an integrated circuit such as a CPU (centralprocessing unit). Hereinafter, this embodiment mode describes an exampleof a CPU to which the semiconductor device shown in Embodiment 1 or 2 isapplied with reference to the drawings.

A CPU 3660 shown in FIG. 7 mainly includes an arithmetic logic unit(ALU) 3601, an ALU controller 3602, an instruction decoder 3603, aninterrupt controller 3604, a timing controller 3605, a register 3606, aregister controller 3607, a bus interface (bus I/F) 3608, an erasableprogrammable ROM 3609, and a ROM interface (ROM I/F) 3620, over asubstrate 3600. The ROM 3609 and the ROM interface 3620 may be providedover different chips. Such a variety of circuits included in the CPU3660 can be formed using the thin film transistor described inEmbodiment Mode 1 or 2; or a CMOS circuit, an nMOS circuit, a pMOScircuit, or the like in which the thin film transistors in EmbodimentMode 1 or 2 are combined.

The CPU 3660 shown in FIG. 7 is merely an example illustrated with asimplified structure, and an actual CPU has a variety of structuresdepending on the usage. Therefore, the structure of the CPU to which thepresent invention is applied is not limited to that shown in FIG. 7.

An instruction input to the CPU 3660 through the bus interface 3608 isinput to the instruction decoder 3603 and decoded therein, and then isinput to the ALU controller 3602, the interrupt controller 3604, theregister controller 3607, and the timing controller 3605.

The ALU controller 3602, the interrupt controller 3604, the registercontroller 3607, and the timing controller 3605 perform various controlsbased on the decoded instruction. Concretely, the ALU controller 3602generates a signal for controlling the driving of the ALU 3601. Whilethe CPU 3660 is executing a program, the interrupt controller 3604judges an interrupt request from an external input/output device or aperipheral circuit based on its priority or a mask state, and processesthe request. The register controller 3607 generates an address of theregister 3606, and reads/writes data from/to the register 3606 inaccordance with the state of the CPU.

The timing controller 3605 generates a signal for controlling timing ofdriving of the ALU 3601, the ALU controller 3602, the instructiondecoder 3603, the interrupt controller 3604, and the register controller3607. For example, the timing controller 3605 is provided with aninternal clock generator for generating an internal clock signal CLK2(3622) based on a reference clock signal CLK1 (3621), and supplies theinternal clock signal CLK2 to the above various circuits.

Here, an example of a CMOS circuit which can be applied to the CPU 3660is shown (see FIG. 8). In the CMOS circuit shown here, a transistor 810and a transistor 820 are formed over a substrate 800 with insulatinglayers 802 and 804 interposed therebetween. Further, an insulating layer830 is formed to cover the transistors 810 and 820, and conductivelayers 840 that are electrically connected to the transistors 810 and/or820 are formed over the insulating layer 830. Furthermore, thetransistors 810 and 820 are electrically connected to each other throughthe conductive layer 840. In the transistors 810 and 820, silicide films850 are formed by the method shown in the above embodiment modes.

For the substrate 800, a substrate having an insulating surface may beused. For example, a glass substrate, a quartz substrate, a sapphiresubstrate, a ceramic substrate, a metal substrate for which aninsulating layer is provided on a surface, or the like can be used.

The insulating layers 802 and 804 are formed by a CVD method, asputtering method, or an ALD method using silicon oxide, siliconnitride, silicon oxynitride, silicon nitride oxide, or the like. Theinsulating layers 802 and 804 function as blocking layers, which preventan alkaline earth metal and the like from diffusing into the transistor810 or 820 from the substrate 800 and thus contaminating the transistor810 or 820. Further, if the substrate 800 has asperities at the surface,the insulating layers 802 and 804 can also function as planarizinglayers. However, it is not necessary to form the insulating layers 802and 804 if impurities diffused from the substrate 800 and asperities ata surface of the substrate 800 do not present any problem. Further, thebase insulating layer may have a single-layer structure or astacked-layer structure including three or more layers although the baseinsulating layer has a two-layer structure here.

The transistor shown in Embodiment Mode 1 or 2 is preferably applied tothe transistors 810 and 820. The transistors 810 and 820 have differenttypes of conductivity. For example, the transistor 810 may be ann-channel transistor, and the transistor 820 may be a p-channeltransistor.

The insulating layer 830 is formed by a CVD method, a sputtering method,an ALD method, a coating method, or the like, using an inorganicinsulating material containing oxygen or nitrogen, such as siliconoxide, silicon nitride, silicon oxynitride, or silicon nitride oxide; aninsulating material containing carbon, such as diamond-like carbon(DLC); an organic insulating material, such as epoxy, polyimide,polyamide, polyvinyl phenol, benzocyclobutene, or acrylic; or a siloxanematerial, such as a siloxane resin. The siloxane material corresponds toa material having Si—O—Si bonds. Siloxane includes a skeleton structureof a bond of silicon (Si) and oxygen (O). As a substituent, an organicgroup containing at least hydrogen (e.g., an alkyl group or aromatichydrocarbon) is used. Alternatively, a fluoro group, or a fluoro groupand an organic group containing at least hydrogen can be used as asubstituent. Further, the insulating layer 830 may also be formed byforming an insulating layer by a CVD method, a sputtering method, or anALD method and then performing high-density plasma treatment thereto inan oxygen atmosphere or a nitrogen atmosphere. Although an example inwhich the insulating layer 830 has a single-layer structure is shownhere, the insulating layer 830 may have a stacked-layer structureincluding two or more layers. Further, the insulating layer 830 may beformed by combining an inorganic insulating layer and an organicinsulating layer.

The conductive layers 840 are formed by a CVD method or a sputteringmethod, using a metal element such as aluminum (Al), tungsten (W),titanium (Ti), tantalum (Ta), molybdenum (Mo), nickel (Ni), platinum(Pt), copper (Cu), gold (Au), silver (Ag), manganese (Mn), or neodymium(Nd), carbon (C), silicon (Si), or an alloy material or compoundmaterial containing the above element, to have a single-layer structureor a stacked-layer structure. As examples of an alloy materialcontaining aluminum, an alloy material containing aluminum as its maincomponent and further containing nickel, and an alloy materialcontaining aluminum as its main component and further containing nickeland at least one of carbon and silicon can be given. The conductivelayers 840 can employ a stacked-layer structure of a barrier layer, analuminum-silicon (Al—Si) layer, and a barrier layer, or a stacked-layerstructure of a barrier layer, an aluminum-silicon layer, a titaniumnitride layer, and a barrier layer, for example. The barrier layercorresponds to a thin film formed of titanium, nitride of titanium,molybdenum, or nitride of molybdenum. Aluminum or aluminum silicon,which has low resistance and is inexpensive, is suitable for forming theconductive layers 840. Further, generation of a hillock of aluminum oraluminum silicon can be prevented if upper and lower barrier layers areprovided.

The conductive layers 840 function as a source electrode and a drainelectrode. The conductive layers 840 are electrically connected to thetransistors 810 and 820 through openings formed in the insulating layer830. Concretely, the conductive layers 840 are electrically connected toa source region and a drain region of the transistor 810, and to asource region and a drain region of the transistor 820. Further, thesource region or the drain region of the transistor 810 is electricallyconnected to the source region or the drain region of the transistor 820through the conductive layer 840. In the above manner, the CMOS circuitcan be formed.

FIG. 9 shows a display device in which a pixel portion, a CPU, and othercircuits are formed over the same substrate: a so-called“system-on-panel”. A pixel portion 3701, a scanning line driver circuit3702 for selecting a pixel included in the pixel portion 3701, and asignal line driver circuit 3703 for supplying a video signal to eachselected pixel are provided over a substrate 3700. A CPU 3704 isconnected to other circuits (e.g., a control circuit 3705) with wiringswhich are led from the scanning line driver circuit 3702 and the signalline driver circuit 3703. The control circuit includes an interface.Further, a connection portion with an FPC terminal is provided at an endportion of the substrate to interact with an external signal.

As other circuits, in addition to the control circuit 3705, for examplean image signal process circuit, a power source circuit, a gray scalepower source circuit, a video RAM, a memory (e.g., DRAM, SRAM, or PROM),and the like can be provided. Such a circuit may be formed using an ICchip and mounted on the substrate. Further, the scanning line drivercircuit 3702 and the signal line driver circuit 3703 are not necessarilyformed over the same substrate: for example, the scanning line drivercircuit 3702 may be formed over the same substrate as that for the pixelportion, and the signal line driver circuit 3703 may be formed using anIC chip and mounted on the substrate.

Although this embodiment mode describes an example in which asemiconductor device according to the present invention is applied to aCPU, the present invention is not particularly limited to thisapplication example. For example, a semiconductor device according tothe present invention can be applied to a pixel portion, a drivercircuit portion, or the like of a display device including an organiclight-emitting element, an inorganic light-emitting element, a liquidcrystal display element, or the like. Furthermore, with application ofthe present invention, the following can also be manufactured: a digitalcamera, an audio reproducing device such as a car audio system, a laptopcomputer, a game machine, a portable information terminal (e.g., amobile phone or a mobile game machine), an image reproducing deviceprovided with a recording medium, such as a home-use game machine, andthe like.

In a semiconductor device to which the present invention is applied,damage to a semiconductor film and a gate electrode is alleviated in amanufacturing process. Further, with application of the presentinvention, variation in characteristics can be suppressed insemiconductor devices such as transistors. Therefore, semiconductordevices with high reliability can be provided in a high yield.

A semiconductor device to which the present invention is appliedincludes silicide films, and thus can have low contact resistance(contact resistance between a conductive layer and a semiconductorlayer); therefore, signal delay and the like can be prevented.Accordingly, a circuit can be driven at high speed.

Embodiment Mode 4

This embodiment mode describes an example of a usage mode of thesemiconductor device described in the preceding embodiment modes.Concretely, an application example of a semiconductor device to/fromwhich data can be input/output without contact is described below withreference to the drawings. The semiconductor device to/from which datacan be input/output without contact is also called an RFID tag, an IDtag, an IC tag, an IC chip, an RF tag, a wireless tag, an electronictag, or a wireless chip depending on the usage mode.

An example of a top structure of a semiconductor device shown in thisembodiment mode is described with reference to FIG. 10A. A semiconductordevice 2180 shown in FIGS. 10A to 10C includes a thin film integratedcircuit 2131 including a plurality of elements such as thin filmtransistors that constitute a memory portion and a logic portion, and aconductive layer 2132 that serves as an antenna. The conductive layer2132 that serves as an antenna is electrically connected to the thinfilm integrated circuit 2131. The thin film transistor described inEmbodiment Mode 1 or 2 of the present invention can be applied to thethin film integrated circuit 2131.

FIGS. 10B and 10C show schematic cross-sectional views of FIG. 10A. Theconductive layer 2132 that serves as an antenna may be provided abovethe elements that constitute the memory portion and the logic portion:for example, the conductive layer 2132 that serves as an antenna can beprovided above the thin film integrated circuit 2131 constituted of thethin film transistors shown in the preceding embodiment modes with aninsulating layer 2130 interposed therebetween (see FIG. 10B). Further,the conductive layer 2132 that serves as an antenna may be provided fora substrate 2133, and then the substrate 2133 and the thin filmintegrated circuit 2131 may be attached to each other so as to sandwichthe conductive layer 2132 (see FIG. 10C). FIG. 10C shows an example inwhich a conductive layer 2136 provided over the insulating layer 2130and the conductive layer 2132 that serves as an antenna are electricallyconnected to each other with conductive particles 2134 contained in anadhesive resin 2135.

Although this embodiment mode describes an example in which theconductive layer 2132 that serves as an antenna is provided in a shapeof a coil and either an electromagnetic induction method or anelectromagnetic coupling method is employed, the semiconductor device ofthe present invention is not limited thereto, and a microwave method maybe employed as well. In a case of a microwave method, the shape of theconductive layer 2132 that serves as an antenna may be determined asappropriate depending on the wavelength of an electromagnetic wave.

For example, when the microwave method (e.g., with an UHF band (in therange of 860 to 960 MHz), a frequency band of 2.45 GHz, or the like) isemployed as the signal transmission method of the semiconductor device2180, the shape such as the length of the conductive layer which servesas an antenna may be set as appropriate in consideration of thewavelength of an electromagnetic wave used for sending a signal. Forexample, the conductive layer which serves as an antenna can be formedinto the shape of a line (e.g., a dipole antenna (see FIG. 11A)), theflat shape (e.g., a patch antenna (see FIG. 11B)), the shape of a ribbon(see FIGS. 11C and 11D), or the like. Further, the shape of theconductive layer 2132 that serves as an antenna is not limited to aline, and the conductive layer in the shape of a curved line, in anS-shape, or in a shape combining them may be provided as well inconsideration of the wavelength of the electromagnetic wave.

The conductive layer 2132 that serves as an antenna is formed using aconductive material by a CVD method, a sputtering method, a printingmethod such as a screen printing method or a gravure printing method, adroplet discharging method, a dispenser method, a plating method, or thelike. As the conductive material, a metal element such as aluminum (Al),titanium (Ti), silver (Ag), copper (Cu), gold (Au), platinum (Pt),nickel (Ni), palladium (Pd), tantalum (Ta), or molybdenum (Mo), or analloy material or compound material containing any of the above metalelements is used, and the conductive layer 2132 employs a single-layerstructure or a stacked-layer structure.

For example, in a case where the conductive layer 2132 that serves as anantenna is formed by a screen printing method, it can be formed byselectively printing a conductive paste in which conductive particleswith a grain diameter of several nm to several tens of μm are dissolvedor dispersed in an organic resin. The conductive particles can be fineparticles or dispersive nanoparticles of one or more kinds of metalsselected from silver (Ag), gold (Au), copper (Cu), nickel (Ni), platinum(Pt), palladium (Pd), tantalum (Ta), molybdenum (Mo), and titanium (Ti),or silver halide. Further, as the organic resin contained in theconductive paste, at least one of organic resins which function as abinder, a solvent, a dispersing agent, and a coating material of metalparticles can be used. Typically, an organic resin such as an epoxyresin and a silicone resin can be given as an example. Further, in forthe conductive layer, it is preferable to bake the conductive pasteafter providing it. For example, in a case of using fine particles(e.g., with a grain diameter of 1 to 100 nm inclusive) containing silveras its main component as a material of the conductive paste, theconductive layer can be formed by baking the conductive paste attemperatures in the range of 150 to 300° C. to harden it. Further, fineparticles containing solder or lead-free solder as its main componentmay be used. In this case, fine particles with a grain diameter of 20 μmor less are preferably used. Solder and lead-free solder have theadvantage of low cost.

In a semiconductor device to which the present invention is applied,damage to a gate electrode and a semiconductor film can be suppressed ina manufacturing process; therefore, a semiconductor device with highreliability can be provided in a high yield. Further, the presentinvention can also be applied to a small semiconductor device to/fromwhich data can be input/output without contact, as described in thisembodiment mode.

Next, an operation example of the semiconductor device of thisembodiment mode is described.

The semiconductor device 2180 has a function of exchanging data withoutcontact, and includes a high-frequency circuit 81, a power sourcecircuit 82, a reset circuit 83, a clock generating circuit 84, a datademodulating circuit 85, a data modulating circuit 86, a controllingcircuit 87 for controlling other circuits, a memory circuit 88, and anantenna 89 (see FIG. 12A). The high-frequency circuit 81 receives asignal from the antenna 89 and outputs a signal received from the datamodulating circuit 86, through the antenna 89. The power source circuit82 generates power source potential from a received signal. The resetcircuit 83 generates a reset signal. The clock generating circuit 84generates various clock signals based on a received signal input fromthe antenna 89. The data demodulating circuit 85 demodulates a receivedsignal and outputs it to the controlling circuit 87. The data modulatingcircuit 86 modulates a signal received from the controlling circuit 87.As the controlling circuit 87, a code extracting circuit 91, a codejudging circuit 92, a CRC judging circuit 93, and an output unit circuit94 are provided, for example. The code extracting circuit 91 extractseach of a plurality of codes included in an instruction sent to thecontrolling circuit 87. The code judging circuit 92 judges the contentof the instruction by comparing each extracted code with a codecorresponding to a reference. The CRC judging circuit 93 detects whetheror not there is a transmission error or the like based on a judged code.In FIG. 12A, in addition to the controlling circuit 87, thehigh-frequency circuit 81 and the power source circuit 82 which areanalog circuits are included.

Next, one example of an operation of the above semiconductor device isdescribed. First, a radio signal is received by the antenna 89 and thensent to the power source circuit 82 through the high-frequency circuit81, so that high power source potential (hereinafter, referred to asVDD) is generated. VDD is supplied to each circuit in the semiconductordevice 2180. A signal sent to the data demodulating circuit 85 throughthe high-frequency circuit 81 is demodulated (hereinafter, this signalis referred to as a demodulated signal). Moreover, signals which havepassed through the reset circuit 83 and the clock generating circuit 84through the high-frequency circuit 81, and the demodulated signal aresent to the controlling circuit 87. The signals sent to the controllingcircuit 87 are analyzed by the code extracting circuit 91, the codejudging circuit 92, the CRC judging circuit 93, and the like. Then,based on the analyzed signals, information of the semiconductor devicewhich is stored in the memory circuit 88 is output. The outputinformation of the semiconductor device is encoded through the outputunit circuit 94. Further, the encoded information of the semiconductordevice 2180 passes through the data modulating circuit 86 and then issent by the antenna 89 as a radio signal. In the plurality of circuitsincluded in the semiconductor device 2180, low power source potential(hereinafter, referred to as VSS) is common and GND can be used as VSS.

In this manner, by sending a signal from a communication unit (e.g., areader/writer or a unit having a function of a reader or a writer) tothe semiconductor device 2180 and receiving a signal sent from thesemiconductor device 2180 with the reader/writer, data of thesemiconductor device can be read.

Further, in the semiconductor device 2180, a power source voltage may besupplied to each circuit with electromagnetic waves without providing apower source (a battery), or a power source (battery) may be provided sothat a power source voltage is supplied to each circuit with bothelectromagnetic waves and the power source (battery).

Next, one example of usage modes of the semiconductor device to/fromwhich data can be input/output without contact is described. A sidesurface of a mobile terminal including a display portion 3210 isprovided with a communication unit 3200, and a side surface of a product3220 is provided with a semiconductor device 3230 (see FIG. 12B). Thecommunication unit 3200 has functions of reading and transmitting asignal like a reader/writer, or has only either function of reading ortransmitting a signal. When the communication unit 3200 is held over thesemiconductor device 3230 included in the product 3220, the displayportion 3210 displays information on the product, such as a rowmaterial, a place of origin, an inspection result for each productionstep, a history of distribution process, or description of the product.Further, when a product 3260 is transferred by a conveyer belt, theproduct 3260 can be inspected with the use of a communication unit 3240and a semiconductor device 3250 provided for the product 3260 (see FIG.12C). As the semiconductor devices 3230 and 3250, the abovesemiconductor device 2180 can be applied. In this manner, with the useof the semiconductor device according to the present invention in thesystem, information can be obtained easily and higher performance and ahigh added value are achieved. Further, the semiconductor deviceaccording to the present invention has high reliability, and inspectionof a product or the like can be performed reliably.

An applicable range of the semiconductor device according to the presentinvention is wide in addition to the above, and the semiconductor devicecan be applied to any product as long as it clarifies information of anobject, such as the history thereof, without contact and is useful forproduction, management, or the like. For example, the semiconductordevice can be provided for bills, coins, securities, certificates,bearer bonds, packing containers, books, recording media, personalbelongings, vehicles, foods, clothing, health products, commodities,medicine, electronic devices, and the like. Examples thereof aredescribed with reference to FIGS. 13A to 13H.

The bills and coins are money distributed to the market, and includewhat is valid in a certain area (a cash voucher), memorial coins, andthe like. The securities refer to checks, certificates, promissorynotes, and the like (see FIG. 13A). The certificates refer to drivers'licenses, certificates of residence, and the like (see FIG. 13B). Thebearer bonds refer to stamps, rice coupons, various gift certificates,and the like (see FIG. 13C). The packing containers refer to wrappingpaper for food containers and the like, plastic bottles, and the like(see FIG. 13D). The books refer to hardbacks, paperbacks, and the like(see FIG. 13E). The recording media refer to DVD software, video tapes,and the like (see FIG. 13F). The vehicles refer to wheeled vehicles suchas bicycles, ships, and the like (see FIG. 13G). The personal belongingsrefer to bags, glasses, and the like (see FIG. 13H). The foods refer tofood articles, drink, and the like. The clothing refers to clothes,footwear, and the like. The health products refer to medicalinstruments, health instruments, and the like. The commodities refer tofurniture, lighting equipment, and the like. The medicine refers tomedical products, pesticides, and the like. The electronic devices referto liquid crystal display devices, EL display devices, televisiondevices (TV sets and low-profile TV sets), mobile phones, and the like.

Forgery can be prevented by providing the semiconductor device 2180 forbills, coins, securities, certificates, bearer bonds, or the like.Further, the efficiency of an inspection system, a system used in arental shop, or the like can be improved by providing the semiconductordevice 2180 for packing containers, books, recording media, personalbelongings, foods, commodities, electronic devices, or the like. Forgeryor theft can be prevented by providing the semiconductor device 2180 forvehicles, health products, medicine, or the like; with regard tomedicine, medicine can be prevented from being taken mistakenly. Thesemiconductor device 2180 can be provided by being attached to a surfaceof an object or being embedded in an object. For example, in the case ofa book, the semiconductor device 2180 may be embedded in the paper; inthe case of a package made of an organic resin, the semiconductor device2180 may be embedded the organic resin.

As described above, the efficiency of an inspection system, a systemused in a rental shop, or the like can be improved by providing thesemiconductor device 2180 for packing containers, recording media,personal belongings, foods, clothing, commodities, electronic devices,or the like. Further, by providing the semiconductor device 2180 forvehicles or the like, forgery or theft thereof can be prevented.Furthermore, by implanting the semiconductor device 2180 in a creaturesuch as an animal, an individual creature can be easily identified. Forexample, by implanting or attaching the semiconductor device with asensor into a creature such as livestock, its health condition such as abody temperature as well as its birth year, sex, breed, or the like canbe easily managed.

This embodiment mode can be freely combined with the precedingembodiment modes.

This application is based on Japanese Patent Application serial No.2007-127081 filed with Japan Patent office on May 11, 2007, the entirecontents of which are hereby incorporated by reference.

1. A method for manufacturing a semiconductor device comprising thesteps of: forming an island-like semiconductor film over an insulatingsubstrate; forming a gate insulating film over the island-likesemiconductor film; forming a gate electrode over the gate insulatingfilm; forming a pair of impurity regions by introducing an impurityelement into the island-like semiconductor film using the gate electrodeas a mask; forming a first metal film which functions as a heatconductive film in a region located over the gate electrode andoverlapping with the gate electrode; forming a second metal film in aregion in contact with the pair of impurity regions, and in a regionlocated over the first metal film and overlapping with the gateelectrode; and irradiating the second metal film with laser light toselectively cause a reaction between the island-like semiconductor filmand the second metal film in the region in contact with the pair ofimpurity regions.
 2. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the laser light is emitted from an excimerlaser.
 3. The method for manufacturing a semiconductor device accordingto claim 1, wherein a channel formation region is formed between thepair of impurity regions, the channel formation region having athickness smaller than a thickness of the pair of impurity regions. 4.The method for manufacturing a semiconductor device according to claim1, wherein a channel formation region is formed between the pair ofimpurity regions, the channel formation region having a thickness of 10to 30 nm.
 5. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the first metal film which functions as aheat conductive film is formed of stainless steel, copper, iron,aluminum or an alloy compound containing any of copper, iron, andaluminum.
 6. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the second metal film is formed of Ni, Co,Ti, or Pt.
 7. The method for manufacturing a semiconductor deviceaccording to claim 1, wherein the insulating substrate is a glasssubstrate, a quartz substrate, a sapphire substrate, a ceramicsubstrate, a metal substrate for which an insulating layer is providedon a surface of the metal substrate.
 8. The method for manufacturing asemiconductor device according to claim 1, wherein the impurity elementis boron or phosphorus.
 9. The method for manufacturing a semiconductordevice according to claim 1, wherein the reaction caused between theisland-like semiconductor film and the first metal film in the region incontact with the pair of impurity regions forms a silicide film.
 10. Amethod for manufacturing a semiconductor device comprising the steps of:forming an island-like semiconductor film over an insulating substrate;forming a gate insulating film over the island-like semiconductor film;forming a gate electrode over the gate insulating film; forming a firstimpurity region and a second impurity region by introducing an impurityelement into the island-like semiconductor film using the gate electrodeas a mask; forming an interlayer insulating film over the gateelectrode; forming a contact hole to expose at least a portion of eachof the first impurity region and the second impurity region by etchingthe interlayer insulating film and the gate insulating film; forming afirst metal film which functions as a heat conductive film over theinterlayer insulating film; removing the first metal film located overthe first impurity region and the second impurity region; forming asecond metal film over the first metal film, and in a region in contactwith the first impurity region and the second impurity region; andirradiating the second metal film with laser light to selectively causea reaction between the island-like semiconductor film and the secondmetal film in the region in contact with the first impurity region andthe second impurity region.
 11. The method for manufacturing asemiconductor device according to claim 10, wherein the laser light isemitted from an excimer laser.
 12. The method for manufacturing asemiconductor device according to claim 10, wherein a channel formationregion is formed between the first impurity region and the secondimpurity region, the channel formation region having a thickness smallerthan a thickness of the first impurity region and the second impurityregion.
 13. The method for manufacturing a semiconductor deviceaccording to claim 10, wherein a channel formation region is formedbetween the first impurity region and the second impurity region, thechannel formation region having a thickness of 10 to 30 nm.
 14. Themethod for manufacturing a semiconductor device according to claim 10,wherein the first metal film which functions as a heat conductive filmis formed of stainless steel, copper, iron, aluminum or an alloycompound containing any of copper, iron, and aluminum.
 15. The methodfor manufacturing a semiconductor device according to claim 10, whereinthe second metal film is formed of Ni, Co, Ti, or Pt.
 16. The method formanufacturing a semiconductor device according to claim 10, wherein theinsulating substrate is a glass substrate, a quartz substrate, asapphire substrate, a ceramic substrate, a metal substrate for which aninsulating layer is provided on a surface of the metal substrate. 17.The method for manufacturing a semiconductor device according to claim10, wherein the impurity element is boron or phosphorus.
 18. The methodfor manufacturing a semiconductor device according to claim 10, whereinthe reaction caused between the island-like semiconductor film and thesecond metal film in the region in contact with the first impurityregion and the second impurity region forms a silicide film.